Task Execution mocking

[nathandf]

Allow users to mock the execution of tasks during a pipeline run by extending the API and Workflow Engine to support a mocks property in requests to runPipeline.

Task Execution Mocks would enable developers and pipeline engineers to:

• run tasks in isolate with mock data
• run subsets of the pipeline graph

Users should be able to

• Define the terminal status of tasks
• Define the outputs of a task
• Connect mocked task executions with real task executions